Functional magnetic resonance lie detection (fMRI) is a new technology in the field of lie detection. It uses neuroscience technology and research methods to detect lies. It combines the knowledge of medicine, law and Criminology. At present, functional magnetic resonance (fMRI) lie detection technology has appeared in relevant litigation cases in the United States. In foreign countries, when using functional magnetic resonance technology to detect lies, we should not only examine its accuracy from a scientific point of view, but also strictly restrict this emerging technology in the field of criminal procedure according to the standard of evidence. This paper analyzes the application of functional magnetic resonance (fMRI) lie detection technology from an overseas perspective, with the help of literature and the case of the federal court of the United States, and discusses the difficulties and challenges encountered by the current functional magnetic resonance lie detection technology, so as to provide an angle for the future development of functional magnetic resonance lie detection technology in China.